Apparatus for bracing a longitudinal mining conveyor



March 12, 1968 APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYORFiled March 1, 1965 5 Sheets-Sheet 1 /NVEN T 0R ARM/N LOBBE A. LOBBE3,372,792

March 12, 1968 V A. LCBBE 3,372,792

APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Filed March 1, 19653 Sheets-Sheet 2 H YD. PRESSURE RETURN f HYD. PRESSURE INVENTQR ARM/NLOBBE March 12, 1968 A. LGBBE 3,372,792

APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Filed March 1, 19653 Sheets-Sheet 5 I 43 REruR/v HYD.

34 RREssuRE HYD. PRESSURE Q/NVENTOR ARM/Iv LO'BBE United States PatentOfilice 3,372,792 Patented Mar. 12, 1968 3,372,792 APPARATUS FOR BRACINGA LONGITUDINAL MINING CONVEYOR Armin Liibbe, Oberaden Post Kamen,Germany, assignor to Gewerkschaft Eisenhutte Westfalia, Wethrnar, nearLunen, Westphalia, Germany, a corporation Filed Mar. '1, 1965, Ser. No.436,397 Claims priority, application Germany, Feb. 28, 1964, G 39,974 12Claims. (Cl. 198126) ABSTRACT OF THE DISCLOSURE This specificationdiscloses a novel prop means adapted to brace a mining conveyor againstthe floor and roof of a mine, so constructed that the mining conveyor iscapable of moving toward and away from the mine seam plane withoutdisturbing the propping action. This apparatus consists of a miningconveyor having an elastically extensible prop member pivotallyconnected to the side thereof away from the mine face, which prop member has a cap pivotally connected therewith which impinges upon the mineroof as the mining conveyor proceeds towards or away from the mine face,the prop member extends or retracts elastically without altering thecontact thereof with the roof.

This invention relates in general to an apparatus for bracing alongitudinal mining conveyor and more particularly to such an apparatushaving one or more extensible propping members connected to the conveyorfor engagement with a roof of a mining seam, and which exert load forcesto brace the conveyor against the floor of the mining seam.

Generally, in the mining of coal and other mineral material, a planingdevice is often used to extract coal from the mine seam face. In thisregard, the planing device is moved against the coal face whereby alayer of coal is scraped from the adjacent mine wall. In order toconveniently remove the extracted coal from the site of miningoperations, a longitudinal conveyor is provided adjacent to the mineface along the path of travel of the planing device.

Accordingly, as the planing device extracts coal, by reason of thepositioning of the conveyor, the coal falls thereon and is conductedfrom the site of mining operations.

in particular, double chain scraper conveyors are used wherein a pair ofparallel endless chains are provided mounted for movement in the samedirection so as to carry the coal by means of the attendant chainscraper bars along the surface of the conveyor to a distant point ofrecovery. The planing device may be conveniently supported in a trackdisposed along the conveyor and afilxed thereto on the side adjacent tothe mine face being extracted.

As each layer of coal is scraped from the mine face, the planing deviceis moved forward in a transverse direction so that it may engage thenext layer of coal. Simi larly, the conveyor is advanced to accommodatethe newly extracted coal.

One of the problems encountered in such mining operation is that ofmaintaining the coal plane track, which is usually mounted laterally onthe conveyor, in a fixed position with respect to the mining seam floorsuch that the coal plane cuts the mining face flush with the floor.Where coal is to be out along an inclined coal bed, it has been foundthat the coal plane guide track frequently rises above the floor as theresult of the high tensions in the conveyor coal chain and the coalplane drive chains, thereby causing said plane to climb upward as itcuts, leaving an uncut layer of coal on the floor.

To remedy this problem it has been proposed to press the conveyortightly against the floor by means of props braced against the roof.However, this proposed solution is not satisfactory in the case ofconveyors and coal planers that are automatically advanced as the coalmining progresses, since the props have to be removed and reset witheach advancement step, an operation which is troublesome andtime-consuming whether the props be wooden props cut to length, orextensible props, such as those that are pneumatically or hydraulicallyoperated.

The apparatus of the instant invention eliminates this disadvantage ofprop setting, and yet provides for positive bracing of the conveyoragainst the floor, by using one or more extensible propping memberspivotally connected to the conveyor, or to a rigid support member suchas a foot member which is affixed to the conveyor, and a cap member foreach propping member which is pivotally connected thereto for hearingengagement with the roof of the mining seam.

The extension length and load force exerted by such a propping membercan be selectively adjusted to maintain the cap member in bearingengagement with the roof and to brace the conveyor against the floor,with said bracing being maintained when the propping member isarticulated to permit the conveyor to be displaced in a directiontransverse to the mining seam face, by providing means which permit thepropping member to yield elastically. In the case of propping memberswhich are hydraulically operated, and are in effect extensible linearactuators, this elastic yielding can be accomplished by means of ahydraulic expansion reservoir, which is flow connected to the fluidpressure chamber of the propping member during articulation, so that asthe length of said propping member is reduced or increased during itsarticulation, the expansion reservoir acts as a hydraulic spring toallow fluid to flow from the propping member into the reservoir whensaid propping member is shortened, and to force fluid back into thepropping member when it is lengthened.

Thus, for example, when the propping member is to be articulated from aninitial position which is inclined away from the mining face to a finalposition which is inclined toward said face, with the cap member beingmaintained in sliding bearing engagement during the articulatingmovement, the length of the propping member must first necessarilydecrease to a minimum in travelling from the initial background inclinedposition to a. position perpendicular to the roof, and the increase inlength as the propping member is swung to the forward inclined position.Accordingly, by reason of the spring effect provided by the expansionreservoir, the cap member is always urged with some force against theroof, even when the propping member is articulated, and although thisforce is not necessarily the same as is exerted when the propping memberis connected directly to its normal hydr-aulic pressure source, theelastic force provided by the expansion reservoir can be made sufiicientto brace the conveyor against the floor. As can be readily appreciatedby those skilled in the art, it is necessary to remove hydraulic fluidfrom the propping member in order to shorten it, and to add fluidthereto in order to lengthen it, due to the substantialincompressibility of liquid hydraulic fluids.

In the typical operation of the apparatus according to the invention,the bracing of the conveyor can be accomplished with the proppingmembers inclined up to a certain limit angle about the perpendicular tothe roof from their pivot connections to the conveyor. This arrangementpermits the propping members to be advanced stepwise by articulation asthe conveyor is advanced. For example, assuming that a propping memberis initially inclined at the limit angle toward the mining face, saidpropping member can be elastically relieved to permit the conveyor to beadvanced toward the mining face by a distance corresponding to anarticulation which inclines the propping member at a backward limitangle, with its cap member remaining in a fixed position against theroof. Then, with the conveyor remaining stationary, and the proppingmember still elastically relieved, said propping member can be swungforward about its pivot connection to the conveyor, with the cap membersliding forward along the roof, to bring said propping member into itsforward limit angle inclination position, thus placing it in anappropriate configuration for a successive advancement step for theconveyor. At the end of each articulation of the propping member, itspressure chamber can be disconnected from the expansion reservoir andconnected to the hydraulic pressure source to increase the bracingforce. It should be noted that when a propping member is initiallyinclined toward the coal face, the conveyor can be advanced for amaximum step distance before the propping member and its cap member mustbe swung forward. This distance corresponds to the path length on theroof swept by the cap member as the propping member is swung from itsbackward to its forward limit angle positions.

This shifting of the cap members ordinarily will not be necessary untilafter several cutting passes of the coal plane, the exact number ofpasses per cap member shift depending upon the depth of cut per pass,and the height of the roof above the propping member pivot axis.

The advancement of the conveyor and its associated coal plane track canbe accomplished by means independent of the propping apparatus, such asfor example, by advancing actuators connected to separate advanceablepropping systems, or by a linear actuator which can be used for botharticulating the conveyor propping members and advancing said conveyor,as provided by another embodiment of the invention.

According to the instant invention, the propping members used forbracing the conveyor are pivotally connected to its side members, withthe pivot axes in each case being substantially parallel to thelongitudinal axis of said conveyor.

Similarly, the cap member is pivotally connected to the extensible upperportion of the propping member with its pivot axis being parallel tothat of the lower portion of said propping member which is connected tothe conveyor. The cap member is so constructed as to have a plate-likeportion which is adapted to engage the roof surface, which can besomewhat irregular.

It has been found advantageous to provide the conveyor with a footmember affixed thereto on the waste side of the conveyor, said footmember being provided with runners which rest upon the floor, and topivotally connect the propping members to such a foot member rather thanto the conveyor directly. With this arrangement the propping members donot interfere with the clearance profile of the conveyor. Also, by usingsuch foot members, it is thus possible to provide propping members forbracing the conveyor at any point along the length of its sides as maybe required for improved bracing action, since such foot member andpropping member arrangements can be conveniently and quickly fastened tothe conveyor such as for example, by bolting.

As long as such a propping member is urged with sufficient force againstthe roof, it will remain in its more or less inclined or perpendicularposition without any further securing. However, a spring such as forexample, a laminated leaf spring, can be provided for the purpose ofmaintaining such a propping member in a raised, inclined position. ifdesired, a hydraulic actuator can be substituted for this purpose. ineither case, the spring or hydraulic actuator are preferably arrangedand attached so that they urge the prop member into its forward positionin the direction of the coal face. Such an arrangement renders theshifting of the propping member more convenient since, as soon as theconveyor has advanced to such an extent that the propping member hasreached its limit rearward inclination, all that needs to be done is tobriefly relieve its pressure against the roof, and it will then be swungautomatically back into its forward position under the effect of thespring or actuator.

Where a hydraulic actuator is used for articulating the propping member,said actuator can be pivotally connected at one end to a support member,or foot member attached to the conveyor, and pivotally connected at theother end to the propping member.

By connecting such an actuator to an independent propping member, suchas a follower propping member, said actuator can also serve foradvancing the conveyor. In such an arrangement it is preferable that thepiston rod of the actuator be pivotally connected to the propping memberat a location close to the pivot connection of said propping member tothe conveyor or foot member, so that the largest possible component offorce exerted by the actuator will serve for advancing the conveyortoward the coal face, while also providing a sufficient but slight forcefor the purpose of swinging the propping member back to its forwardposition after its pressure against the roof has been elasticallyrelieved.

If desired, propping members can be connected to the coal-face side ofthe conveyor in addition to, or instead of the propping membersconnected to its waste side. In such an arrangement, it is expedient toconnect the propping members on the coal-face side to articulate in thesame plane as the oppositely connected propping members on the wasteside, such as for example, by a linking member connecting pairs ofopposite propping members, or by articulating their cap members to oneanother. Furthermore, the pressure chambers of such articulatelyconnected propping members can be operated from a common hydrauliccontrol means.

According to the instant invention, the hydraulic fluid flow to and fromsuch actuators and hydraulic propping members can be performedautomatically by means of control valves operated in response to theangular position of the propping members so that the sequence ofarticulating motions that must be performed with each advancement stepof the conveyor can be performed automatically.

It is therefore, an object of the invention to provide an apparatus forbracing a mining conveyor and its associated coal plane track againstthe floor of a mining seam, so that the coal plane will remove coal fromthe mining face down to a level which is flush with the seam floor.

Another object of the invention is to provide an apparatus as aforesaidwherein the bracing of the conveyor and coal plane track is maintainedduring the advancement thereof, so that on successive coal planingoperations. coal from the mining face will be removed down to the floor.

Still another and further object of the invention is to provide anapparatus as aforesaid having articulating advanceable propping memberswhich can be attached as required to various locations along either orboth sides of the conveyor.

Another object of the invention is to provide an apparatus as aforesaidwherein the articulation of the propping members can be performedautomatically with each advancement of the conveyor.

Other objects and advantages of the invention will become apparent fromthe following detailed descriptions and accompanying drawings in which:

FIG. 1 is a tranverse cross section of a mining seam, showing operatingarrangement of an apparatus according to a preferred embodiment of theinvention.

FIG. 2 is a plan view of FIG. 1

FIG. 3 is a transverse section to a mining seam, similar to that of FIG.1, showing an operating arrangement of an apparatus according to anotherpreferred embodiment of the invention.

FIG. 4 is a schematic illustration of a hydraulic control system for theapparatus of FIG. 1.

FIGS. 5A and 5B are schematic illustrations of a modified hydrauliccontrol system for the apparatus of FIG. 1.

Referring now to FIGS. 1 and 2, which show an apparatus A according tothe invention for bracing a conveyor trough 10, a ramp-like guide rail11 for a coal plane 12 is attached to the coal-face side of the conveyor10. For simplicity, the circulating drag chain used for pushing coalover into the conveyor has been omitted.

The coal plane 12 is driven in alternating directions along thecoal-face 14 by a chain 13, which is in turn driven by a prime mover(not shown).

For an eficient mining operation, it is essential that the plane 12 cutaway coal from the coal-face 14 all the way down to the level of thefloor of the mining seam. To accomplish this, it is necessary that theguiding track 11 and attached conveyor 10 be maintained in such aposition, preferably against the floor 15, that the plane 12 can cutflush with the level of said floor 15.

It has been found, especially in inclined mining seams, that the highlytensioned conveyor chains (not shown), and the coal plane 12 drive chain13 tend to lift the conveyor 10 and track 11 up away from the floor 15,thereby causing the plane 12 to climb upward, leaving a layer of uncutcoal extending above the level of said floor 15.

According to the invention, the conveyor 10 and guide track 11 arebraced against the floor 15 by means of an apparatus A, having anextensible propping member 16 which is pivotally connected by a pin 17to a foot member 18 which is fixedly, but releasably connected to theconveyor 10. If desired, this pivotable connection can be made directlyto the conveyor 10 or to any suitable support member (not shown)attached thereto. However, the use of a foot member 18 which can bereleasably connected to the conveyor 11) for carrying the pivotalconnection 17 of the propping member 16 has been found to be moreadvantageous, since such a foot member 18 can be attached to theconveyor 10 at a multiplicity of selected locations thereon, andadditional members 16 can be attached to said conveyor 10 as desired orrequired along its length.

The foot member 18 is preferably provided with runners 19 at its bottom,said runners 19 being disposed perpendicular to the coal-face 14, andare adapted for hearing engagement with the floor 15. Depending upon thearrangement of the guide track 11 with respect to the conveyor 10, thefoot member 18 can be connected to said conveyor 10 so as to maintainboth the foot member 18 and conveyor 10 in contact with the fioor 15, orsaid foot member 18 and conveyor 10 can be connected so that theconveyor 10 is maintained at a fixed spacedapart distance from the floor15 when the runners 19 of the foot member 18 are in contact with saidfioor 15, the choice of foot member 18 to conveyor 10 connectionarrangement being preferably the one which holds the track 11 in aposition which causes the coal plane 12 to cut the coal-face 14 down tothe level of said floor 15.

The propping members 16 are preferably of the conventional hydraulicallyoperated type, which are substantially equivalent in operation tohydraulic linear ac- Iuators in that they have a pressure chamber orcylinder 30 and a piston member 31 slidably disposed therein. By meansof the hydraulic pressure control system shown in FIG. 4, said proppingmember 16 can be selectably adjusted in its extension length as well asin the load force it exerts to brace the foot member 18 and conveyor 10against the floor 15.

Under the effect of the hydraulic fluid transmitted from a source (notshown) by means of a hydraulic line 20, the cap member 16 which ispivotally connected to the piston or upper member 31 of said proppingmember 16 is urged into bearing engagement against the roof 21 so thatthe load force exerted by the propping member 16 acts to brace the footmember 18 against the floor 15.

By placing the pressure cylinder 30 of the propping member 16 in flowconnection with the hydraulic expansion reservoir 24 as indicated byFIG. 4, the propping member 16 can be rendered elastic, so as to haveextension properties equivalent to those produced if a compressionspring (not shown) were introduced into the pressure cylinder 30,instead of hydraulic fluid. This elasticity serves to maintain the uppermember 31 yieldingly extend-ed, but under pressure to maintain the capmember 16' in bearing contact with the roof 21 as the propping member 16assumes various inclined positions when it is articulated from a forwardlimit inclination angle to backward limit inclination angle as shown bythe broken outlines I and II in FIG. 1.

This articulation capability is advantageous in that it permits conveyor10 to be braced with respect to the floor 15 during times when it isdisplaced in a direction transverse to the coal-face 14, and alsopermits such a displacement to be performed. Without elasticallyrelieving the hydraulic pressure in the cylinder 30, as by allowing itto flow into an expansion reservoir 24, the incompressibility of thefluid in said cylinder 31} would prevent the advancement of the conveyor10 and coal plane 12 toward the coal-face 14.

The advancing of the conveyor 10 and its associated coal plane 12 can beaccomplished by independent actuators 22, preferably hydraulic, whichare braced against roof props 23, and are connected to the: conveyor 10as indicated by FIG. 2.

The basic operation of the bracing apparatus A, can be best explained byassuming that the propping member 16 is in an initial position I asindicated by the broken outline of FIG. 1, wherein said propping member16 is inclined at its forward limit angle, and that it is desired toadvance the conveyor 10 toward the coal-face 14 as indicated by the fullline configuration of FIG. 1. To accomplish this the propping member 16is elastically relieved by connection to the expansion reservoir 24, andthe actuators 22 are operated to advance the conveyor 10 toward the coalface 14. As the conveyor 10 is so advanced, the propping member 16 isfirst shortened and then lengthened elastically as it articulates fromits backward limit angle position to its forward limit angle position,as indicated by the broken outlines I and II of FIG. 1. During thisarticulation, the cap member 16' remains fixed in its original position,and braces the conveyor 10. When the propping member 16 is in theforward limit angle position II, it is again articulated forward, withthe cap member 16 being swept along the roof 21 until the proppingmember 16 and cap member 16' are: in the full line position of FIG. 1.During the second articulation the conveyor 10 is held stationary.

This procedure can be repeated to successively advance the conveyor 10during the progress of coal mining, and need not be performed in twosteps, as in the case where it is desired to continuously advance theconveyor 10.

The apparatus A of the instant invention is adaptable to the gradual andcontinuous advancement of the conveyor 10 since it makes no dilferencein the bracing action whether the propping member 16 is graduallyarticulated between its limit angle positions or is stepwisearticulated. However, in the case of the stepwise articulation of saidpropping member 16 and advancement of the conveyor 10, the hydraulicpressure loading of said propping member 16 can be raised to a higherlevel at the end of each step, so as to provide firmer bracing, whereasin the case of gradual continuous advancement where the propping member16 must be maintained in an elastically yielding condition, an extremehydraulic pressure loading would not be feasible. Since a sullicientlyhigh pressure loading can be maintained for adequate bracing of theconveyor 10 even where the propping member 16 is in the elastic yieldingcondition, provided that sufficient force is available from theadvancing actuators 22, there should be no difficulty encountered whereit is desired to advance the conveyor 10 continuously.

According to the preferred embodiment of the invention exemplified byFIGS. 1 and 2, the articulation of the propping member 16 is performedby means of a hydraulic linear actuator which can also be operated fromthe hydraulic line 23 by means of the control valve arrangement of FIG.4.

Since, ordinarily, it will be desired only to swing the propping member16 into a forwardly inclined position, a spring (not shown), such as forexample a leaf spring (not shown) can be substituted for the actuator25. As shown in FIG. 4, the actuator 25 is connected by a line 32 to acontrol valve 33, preferably a three-way valve, which is connected tothe hydraulic pressure line 20, and the return line 34 from thehydraulic pressure source (not shown), said return line 34 being at alower pressure than the line 20. The valve 33 is capable of selectablyconnecting the line 32 to either the pressure line 20 or to the returnline 34.

The pressure cylinder of the propping member 16 is connected by a line35 to another control valve 36 which is also a three-way valve, andwhich serves to selectably connect the cylinder 36 to either thepressure line 21), or to a line 37 which is connected to the expansionreservoir 34.

When it is desired to articulate the propping member 16 either forwardor backward, the valve 36 is operated to place the cylinder 30 andexpansion reservoir 34 in flow connection, thus enabling said proppingmember 16 to yield and extend elastically.

When it is desired that the propping member 16 be articulated backwardlyas when the conveyor 10 is advanced, the valve 33 is operated to placethe actuator 25 in flow connection with the return line 34, so that thefluid in said actuator can flow back to the source as its piston 38 ispushed into the cylinder 39 thereof by the backward articulation of thepropping member 16.

To provide for bracing the actuator 25 so that it is effective toarticulate the propping member 16, its cylinder 39 is pivotallyconnected to the foot member 18 by a pin 40, and its piston 38 ispivotally connected to the cylinder 39 of the propping member 16 by apin 41.

When it is desired to articulate the propping member 16 in the forwarddirection, as when the cap member 16 is to be swept long the roof 21,the valve 33 is operated to place cylinder 39 of said actuator 25 inflow connection with the pressure line 2t), so that the piston 38 isforcibly urged Outward therefrom to articulate the propping member 16forward.

The two views (A) and (B) of FIG. 5 schematically illustrate anotherhydraulic control arrangement whcih can be use-d in conjunction with theapparatus A of FIGS. 1 and 2.

In this particular arrangement, the propping member 16a is adouble-acting hydraulic linear actuator having a lower cylinder portion30a and an upper cylinder portion 30b and a piston 31. The cylinder 39of the actuator 25 is flow connected with the upper cylinder portion3011 by a line 42, said line 42 being also connected to a threewaycontrol valve 43 by a line 44. The lower cylinder portion 30a isconnected by a line 45 to another three-way control 46. The valves 43and 46 are connected to each other by a line 47, which in turn isconnected by a line 48 to a three-way control valve 49. In addition, thevalves 43 and 46 are connected to the return line 34 by lines 50 and 51,respectively. A line 52 connects the valve 49 to the expansion reservoir24.

The view (A) shows the propping member 16a in its forward inclinationlimit position, with its lower cylinder portion 33a connected via thevalves 46 and 49 to receive elastically pressurized fluid from thereservoir 24, with its upper cylinder portion 30b and the cylinder 39 ofthe actuator 25 being connected via the valve 43 to the return line 34.Under such conditions, the piston 31 is driven outward and upward topress the cap member 16 firmly against the roof 21, and the actuator 25is de-e-nergized. If desired, firmer bracing can be obtained byswitching the valve 49 to cut out the reservoir 2.4, and to connect theline 48 directly to the pressure line 2-0.

In the valve positions (valves 43, 46, and 49) shown in view (A), thepropping member 16a can be articulated 'backwardly with the cap member16' remaining fixed against the roof 21 simply by pushing the conveyor14 and foot member 13 forward. With the upper cylinder portion 38b andthe actuator 25 connected to the return line 34, the piston 31 will beextended and retracted automatically by the elastic action of thereservoir 24.

When the propping member 1611 has arrived at its backward limit angleposition, such as indicated by view (B), the valve 43 is operated toconnect the actuator 25, cylinder 39 and the upper cylinder portion 33bto receive pressurized hydraulic fluid, and the valve 46 is operated toconnect the lower cylinder portion 30a to the return line 34. The valve49 can be operated to connect the reservoir 24 into the pressure line20, or if desired, the reservoir 24 can be cut out entirely. Under theseconditions, the piston 31 is driven inward, relieving pressure exertedby the cap member 16 against the roof 21 momentarily, as the proppingmember 16a is swung forward by the energized actuator 25.

The backward and forward articulation of the propping member 16a can beperformed automatically by means of a switching mechanism 53 which isresponsive to the angular position of said propping member 16a, or by aswitching member 53 which is responsive to the extension of the actuator25, since in the arrangements shown in FIG. 5, the extension of saidactuator 25 is directly related to the angular position of the proppingmember 16a. in either case, the mechanism 53 operates the valves 43, 46and 49 in response to the angular position of the propping member 16a soas to accomplish the desired articulation thereof automatically. As tothe details of the mechanism 53, any conventional switching devicesuitable for the purpose can be used. Where the valves 43, 46 and 49 areelectrically operable, such as solenoid controlled valves, the switchingmechanism 53 is preferably an electrical switching device.

It will be appreciated by those skilled in the art, that other valveswitching sequences and control arrangements can be substituted forthose described herein by way of example.

As can be noted in FIG. 1, another propping member 27, indicated inbroken lines, can be provided in addition to or instead of the proppingmember 16. This propping member 27 serves to provide additional bracingfor the conveyor 19, and is articulately connected thereto at itscoalface side, and is provided with a pivotally connected cap member27'.

The propping member 27 is preferably arranged so as to assume a positionparallel to that of the propping member 16. This can be achieved byconnecting the cap member 16 and 27' articulately, such as by a linkmember 54. If desired, the link member 54 can be alternatively connecteddirectly to the propping members 1.6 and 27, so that the same means usedfor articulating the propping member 16 will produce a correspondingarticulation in propping member 27. The extension length and load forceexerted by the propping member 27 can be controlled by simply connectingits pressure cylinder 55 in parallel with the hydraulically operatedcylinder 30 of propping member 16.

A somewhat different embodiment of the invention is shown by theapparatus A of FIG. 3. The propping member 16 in this case is urgedforward towards the coal face 14- by advancing cylinder 28, which is inturn braced against a sprag 29. This arrangement offers the advantagethat the same pressure cylinder 28 can perform both the function ofadvancing the conyeyor it} along with the coal plane guide track 11, andthe function of articulating the propping member 16 as previouslydescribed herein. If desired, a separately advanceable propping system(not shown) can be substituted for the sprag 29.

What is claimed is:

1. An apparatus for bracing a mining conveyor against the floor of amining seam having a floor, a roof, and a mining face which comprises:

(a) an extensible propping member connected at one end to the miningconveyor through pivot pins which are disposed substantially parallel tothe longitudinal axis of said conveyor, and adapted to be positioned ina plane substantially perpendicular to said axis;

(b) a cap member pivotally connected to the opposite end of saidpropping member for hearing engagement with the roof of the mining seam;

(c) means for selectively adjusting the extension length and load forceexerted by said propping member to maintain the cap member in bearingengagement with the roof and brace the conveyor against the floor, andto maintain said bracing of the conveyor when the propping member isarticulated to permit said conveyor to be displaced in a directiontransverse to the seam face; and

(d) resilient force structure in constant reaction with said proppingmember.

2. The apparatus according to claim 1 including a rigid support memberfixedly connected to the conveyor, and an extensible linear actuator forarticulating the propping member, said actuator being pivotallyconnected at one end to said propping member and pivotally connected atthe opposite end to said support member, and means for selectivelyadjusting the extension of said actuator to articulate said proppingmember.

3. The apparatus according to claim 1 including a bracing memberdisposed in fixed spaced relation to the face of the mining seam, anextensible linear actuator for selectively displacing the conveyor in adirection transverse to said seam face and articulating the proppingmember, said linear actuator being pivotally connected at one end to thebracing member, and pivotally connected at the opposite end to saidpropping member, and means for selectively adjusting the extension ofsaid actuator to displace the conveyor and articulate the proppingmember.

4. The apparatus according to claim 1 wherein the extensible proppingmember is a hydraulic linear actuator, and the means for selectivelyadjusting the extension length and load force exerted by said proppingmember includes a source of pressurized hydraulic fluid, a hydraulicfluid expansion reservoir, and a control valve flow connected to saidreservoir, to the propping member, and to the hydraulic fiuid source,said valve being selectively operable to place the propping member inflow connection with the source, and to place said propping member inflow connection with the reservoir, whereby when said propping member isto be articulated, the valve is operated to place the propping member inflow connection with the reservoir, thereby enabling said proppingmemher to ext-end and contract as required for its articulation, and tomaintain the conveyor braced against the floor during such articulationwith a load force which is established by the quantity of hydraulicfluid transferred from the propping member into the reservoir, and atthe end of said articulation, the valve is operated to place thepropping member in flow connection with the hydraulic fluid source toincrease the bracing force acting on the conveyor.

5. The apparatus according to claim 4 including a hydraulic linearactuator which is selectively extensible for articulating the proppingmember, said actuator being pivotally connected at one end to saidpropping member and pivotally connected at the other end to a supportmember which is fixedly connected to the conveyor, a source ofpressurized hydraulic fluid, said source having a pressure line and areturn line, and a control valve flow connected with said actuator, andwith said pressure and return lines, said valve being selectivelyoperable to place the actuator in flow connection with the pressure linefor articulating the propping member in a. direction toward the miningface, and to place said actuator in flow connection with the return lineto permit said propping member to be articulated in the reversedirection.

6. An apparatus for bracing a mining conveyor With respect to the floorof a mining seam having a floor, a roof and a mining face, whichcomprises:

(a) an articulatable elastically extensible hydraulic propping memberhaving means for bearing engagement with the roof adapted to exert athrust on said mining conveyor during articulation thereof;

(b) means for pivotally connecting said propping member to the conveyor;

(c) hydraulic means for selectively adjusting the extension length andload force exerted by said propping member to brace the conveyor withrespect to the floor and for maintaining said bracing when the proppingmember is articulated;

(d) an actuator for articulating said propping member from a backwardlyinclined position;

(e) control means responsive to the inclination angle of said proppingmember for controlling the operation of said actuator; and

(f) resilient force structure in constant reaction with said proppingmember.

7. An apparatus for maintaining an advanceable mining conveyor in fixedspaced-apart relation to the floor of a mining seam having a floor, aroof, and a mining face, which comprises:

(a) a foot member fixedly connected to the conveyor,

said foot member being supported in bearing engagement by the floor;

(b) an elastically extensible propping member connected at one end tosaid foot member through pivot pins which are disposed substantiallyparallel to the longitudinal axis of said conveyor, and adapted to bepositioned in a plane substantially perpendicular to said axis;

(c) a cap member pivotally connected to the opposite end of saidpropping member for bearing engagement with the roof;

(d) means for selectively adjusting the extension length and load forceexerted by said propping member to maintain the cap member in bearingengagernent with the roof, and the conveyor in fixed spacedapartrelation to the floor by bracing the foot member against said floor, andto maintain said bracing when the propping member is articulated topermit said conveyor to be displaced in a direction transverse to theseam face; and

(e) resilient force structure in constant eraction with said proppingmember.

8. The apparatus according to claim 7 wherein the conveyor is connectedto the foot member in an arrange ment whereby both the foot member andthe conveyor are in bearing engagement with the floor.

9. The apparatus according to claim 7 including an extensible linearactuator for articulating the propping member, said actuator beingpivotally connected at one end to said propping member, and pivotallyconnected at the opposite end to the foot member, and means forselectively adjusting the extension of said actuator to articulate saidpropping member.

10. An apparatus for bracing a longitudinal mining 11 i conveyor againstthe floor of a mining seam having a floor, a room, and a mining face,said conveyor having a pair of oppositely disposed side members, one ofwhich faces the mining face, with the other facing the waste side of themining seam, which comprises:

(a) a foot member fixedly connected to the Waste side member of theconveyor, said foot member being supported in bearing engagement by thefloor;

(b) a first elastically extensible propping member connected at one endto said foot member through pivot pins which are disposed substantiallyparallel to the longitudinal axis of said conveyor, and adapted to bepositioned in a plane substantially perpendicular to said axis;

(c) a first cap member pivotally connected to the opposite end of saidfirst propping member for bearing engagement with the roof;

(d) a second extensible propping member pivotally connected at one endto the mining face side member of the conveyor;

(e) a second cap member pivotally connected to the opposite end of saidsecond propping member for bearing engagement with the roof;

(f) means for selectively adjusting the extension lengths and loadforces exerted by said first and second propping members to maintaintheir respectively connected cap members in bearing engagement with theroof, and to hold the conveyor braced 1?. against the floor, and tomaintain said bracing when the propping members are articulated topermit the conveyor to be displaced in a direction transverse to theseam face; and

(g) resilient force structure in constant reaction with said proppingmember.

11. The apparatus according to claim 10 including linkage meansoperatively connected to the first and second propping members forarticulating them in synchronism.

12. The apparatus according to claim 11 including an extensible linearactuator for articulating the propping members, said actuator beingpivotally connected at one end to the foot member, and pivotallyconnected at the opposite end to the first propping member, and meansfor selectively adjusting the extension of said actuator to articulatesaid propping members.

References Cited UNITED STATES PATENTS 3,072,241 1/1963 Rosenberg et a1.198-126 3,113,661 12/1963 Linke et a1. 198l26 EDWARD A. SROKA, PrimaryExaminer.

EVON C. BLUNK, Examiner.

A. C. I-IODGSON, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,372,792 March 12, 1968 Armin Lobbe It is certified that error appearsin the above identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, lines 7 and 8, "mining" should read winning line 50, "theincrease" should read then increase Column 6, line 62, "mining" shouldread winning Column 7, line 53,-"long" should read along Column 10, line62, "eraction" should read reaction Column 11, line 2, "a room" shouldread a roof Signed and sealed this 25th day of November 1969.

( Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

